1) Field of the Invention
The invention herein relates to measuring instruments, specifically a drive-type tape rule wherein a spring disposed inside the blade take-up spool constitutes a spring-loaded wheel that is installed at one or two sides of the blade take-up spool, enabling the blade take-up spool to accommodate the winding of a tape ruler blade that is approximately 2 to 2.5 times longer than that possible with a conventional blade take-up spool of the same diameter and, furthermore, the torque of the spring-loaded wheel rewinds of the tape ruler blade, thereby enhancing tape rule utility and performance.
2) Description of the Prior Art
A conventional tape rule utilizing an internal blade take-up spool consists of a concentric spring at the center and a tape ruler blade wound around the exterior, a hook riveted to the front end of the tape ruler blade, and a center shaft projecting from the inner side of a left case half for inserting the center section of the spring in the blade take-up spool; screws are respectively inserted through mounting holes in the right case half on the other side and fastened to the center shaft and mounting posts of the left case half to thereby assembly the said tape rule. Evaluating the structure of the conventional tape rule, since there is a concentric spring centrally coiled in the said blade take-up spool, the said spring occupies space at the center of the blade take-up spool, and the remaining space is used for winding the tape ruler blade, a conventional tape ruler blade can only be a length of approximately 5 to 7.5 meters; additionally, extending the length of the tape ruler blade requires an increase in the diameter of the blade take-up spool and, at the same time, when the tape ruler blade is utilized for measurements and pulled out longer distances, the rewinding torque of the spring must be considered in that additional space will be needed to fit a stronger spring; however, to meet ergonomic concerns, since the maximum dimensions of the tape rule case is limited to what the average hand is capable of grasping, increasing the diameter of the blade take-up spool is difficult. As a result, to facilitate tape rule usage, the applicant of the invention herein conducted extensive research and development based on many years of specialized production experience to further enhance the practical value of the invention herein which following repeated testing and refinement culminated in the drive-type tape rule of the present invention.
Therefore, the primary objective of the invention herein is to provide a drive-type tape rule in which a spring-loaded wheel is installed in one or two sides of the blade take-up spool, enabling the tape ruler to have case dimensions that facilitate manual grasping in accordance with ergonomic principles, the said blade take-up spool has the capacity to wind a tape ruler blade of greater length that is approximately 2 to 2.5 times longer and, furthermore, the spring-loaded wheel provides torque to rewind the tape ruler blade, thereby enhancing tape ruler utility and performance.
To enable the examination committee a further understanding of the structural features, innovative content, and advantages of the invention herein, the brief description of the drawings below are accompanied by the detailed description of the embodiments.